Fix open_command nohup call
Fix open_command nohup call

There a syntax error if $cmd_var contains more than one word,
so we drop the current way to prepend nohup and use a simpler
if-else form.

xluoly/oh-my-zsh,xluoly/oh-my-zsh,xluoly/oh-my-zsh,xluoly/oh-my-zsh